Method using immobilized yeast to produce ethanol and alcoholic beverages

Abstract

According to the invention, yeast cells are immobilized on a substantially noncompressible carrier having anion exchange properties. The immobilized yeast can then be used to ferment a sugar-containing substrate. The noncompressibility enables the system to be sterilized and to operate under pressure. A preferred example of the carrier is granular DEAE cellulose.

What is claimed is: 
     
       1. A method of producing an ethanolic product in a primary fermentation comprising: obtaining a reactor loaded with an aqueous mixture of a substantially noncompressible positively charged carrier having anion exchange properties;   eluting the loaded reactor with an aqueous mixture of yeast broth to cause the yeast to become immobilized through electrostatic forces on the carrier;   passing an aqueous substrate containing a fermentable sugar through the reactor containing immobilized yeast cells to produce the ethanolic product.   
     
     
       2. A method for producing an ethanolic product in a primary fermentation comprising: loading a reactor with an aqueous mixture of a substantially noncompressible positively charged carrier having anion exchange properties, to produce a loaded reactor;   sterilizing the loaded reactor;   eluting the loaded reactor with a yeast broth to cause the yeast to become immobilized through electrostatic forces on the carrier;   passing an aqueous substrate containing a fermentable sugar through the reactor containing immobilized yeast to produce the ethanolic product.   
     
     
       3. A method according to claim 2 further comprising recovering the eluant from the passage of the aqueous substrate through the reactor, thereby producing the ethanolic product. 
     
     
       4. A method according to claim 1 or 2 wherein a consumable ethanolic product is produced and the aqueous substrate is a fruit or vegetable juice, a fruit or vegetable extract, a cereal grain extract or wort, hydrolyzed plant material or a sugar syrup. 
     
     
       5. A method according to claim 1 or 2 wherein the carrier comprises a continuous, porous matrix, or dimpled or reticulated, porous particles, the matrix or particles having a structure formed from a loosely associated plurality of microparticles or microfibers which are chemically, adherently or mechanically bound together at least at some contact points between the individual microparticles or microfibers. 
     
     
       6. A method according to claim 5 wherein the microparticles or microfibers forming the particles are composed of an anion exchange resin. 
     
     
       7. A method according to claim 5 wherein the microparticles or microfibers are composed of an anion exchange resin selected from the group consisting of native or regenerated cellulose derivatized to provide anion exchange character, a -phenol-formaldehyde anion exchange resin, an agarose anion exchange resin and a dextrin anion exchange resin. 
     
     
       8. A method according to claim 7 wherein the anion exchange resin is a native or regenerated cellulose that is derivatized to provide anion exchange character. 
     
     
       9. A method according to claim 7 wherein the microparticles or microfibers are bound together by adherent links. 
     
     
       10. A method according to claim 7 wherein the carrier comprises particles formed from microfibers agglomerated with polystyrene and the anion exchange resin is diethylaminoethylene substituted cellulose. 
     
     
       11. A method according to claim 1 or 2 comprising passing the aqueous substrate through a plurality of reactors connected in series by means for removing gas from the fluid eluted from each reactor. 
     
     
       12. A method according to claim 1 or 2 wherein the aqueous substrate is passed through the reactor at a pressure sufficient to maintain in a dissolved state a substantial portion of the carbon dioxide produced. 
     
     
       13. A method according to claim 12 wherein the pressurization is substantially maintained throughout the production and subsequent steps, thereby producing a carbonated ethanolic product. 
     
     
       14. A method according to claim 1 or 2 wherein industrial ethanol is produced. 
     
     
       15. A method according to claim 1 or 2 wherein consumable ethanol is produced. 
     
     
       16. A method according to claim 1 or 2 wherein the feed rate and reactor residence time are adjusted so as to provide an ethanolic product with an ethanol concentration of from about 0.05 to about 15 percent by volume relative to the total volume of the product. 
     
     
       17. A method according to claim 1 or 2 wherein the flow of aqueous substrate through the reactor is in a direction against the force of gravity. 
     
     
       18. A method according to claim 1 or 2 wherein the flow of aqueous substrate through the reactor is periodically reversed. 
     
     
       19. A method according to claim 1 or 2 wherein the carrier is a continuous matrix or a multitude of dimpled or reticulated, porous particles. 
     
     
       20. A method according to claim 1 or 2 wherein the reactor is a column. 
     
     
       21. A method according to claim 1 or 2 further comprising regenerating the fermentation capacity of a reactor with spent, unproductive yeast by removing the unproductive yeast from the carrier packed within the reactor, sterilizing the packed carrier, and passing new yeast broth through the reactor to cause new yeast cells to become immobilized upon the carrier.